Correcting Sonic 1 PAL Music Tempo

This is a fix for a problem that not that many people are going to experience; I have a flash cart and a PAL console and it annoys the shit out of me that the music is slow. (Actually, the whole game is slower, but whatever)

What this does is run the sound driver a second time every 5th frame, increasing the tempo to match the NSTC tempo.

First we need to find a free byte in ram to keep count of how many times the sound driver has been run.